OpiniãoThe Xpert MTB/RIF assay is a cartridge-based automated test that uses realtime polymerase chain reaction (PCR) on the GeneXpert platform to identify MTBC and mutations associated with RIF resistance directly from sputum specimens in less than 2 hours. WHO recommends using the Xpert MTB/RIF test in the following situations (7):
- In adults with signs and symptoms of pulmonary TB, Xpert MTB/RIF should be used as an initial diagnostic test for TB and detection of RIF resistance rather than smear microscopy, culture and phenotypic DST.
- In children with signs and symptoms of pulmonary TB, Xpert MTB/RIF should be used in sputum, gastric aspirate, nasopharyngeal aspirate or stool specimens as the initial diagnostic test for TB and detection of RIF resistance detection, rather than smear microscopy or culture and phenotypic DST.
- In adults and children with signs and symptoms of TB meningitis, Xpert MTB/RIF should be used in cerebrospinal fluid (CSF) as an initial diagnostic test for TB meningitis rather than smear microscopy or culture.
- In adults and children with signs and symptoms of extrapulmonary TB, Xpert MTB/RIF may be used in lymph node aspirate, lymph node biopsy, pleural fluid, peritoneal fluid, pericardial fluid, synovial fluid or urine specimens as the initial diagnostic test for the corresponding form of extrapulmonary TB rather than smear microscopy or culture.
- In adults and children with signs and symptoms of extrapulmonary TB, Xpert MTB/RIF should be used for detection of RIF resistance rather than culture and phenotypic DST.
- In HIV-positive adults and children with signs and symptoms of disseminated TB, Xpert MTB/ RIF may be used in blood, as a diagnostic test for disseminated TB.
- In children with signs and symptoms of pulmonary TB in settings with pretest probability below 5% and an Xpert MTB/RIF negative result on the initial test, repeated testing with Xpert MTB/RIF in sputum, gastric fluid, nasopharyngeal aspirate or stool specimens may not be used.
- In children with signs and symptoms of pulmonary TB in settings with pretest probability of 5% or more and an Xpert MTB/RIF negative result on the initial test, repeated testing with Xpert MTB/RIF (for a total of two tests) in sputum, gastric fluid, nasopharyngeal aspirate and stool specimens may be used.
Note: The Xpert MTB/RIF has been superseded by the Xpert MTB/RIF Ultra. The product has been discontinued globally and will not be available in 2024 except in a few selected countries (e.g. India and the USA).